While I don’t agree that the females should be better looking (finally real women in games, yay), I do agree about that “derpy” look. But I think it is influenced by two factors.
One is, like mentioned before by Kakyou, the hair and eye shader. They still look dull and kind of plastic or glassy, not fitting to the rest of the face. It’s been a topic a few times, especially about Henry.
The second is this kind of naive demeanor the girl impresses. It’s something I personally don’t like but was probably chosen to show youth and kindness. And actually is found in Henry’s big eyed face, too.
Those two people don’t look like the typical hero or heroine you usually encounter in videogames. In western games, the man always looks fierce and edgy while you get a choice between lolita or hot model for the woman. And as much as it takes to getting used to those unexpected looks, I really endorse Warhorse for taking another route.
If their looks aren’t your eye candy, maybe their personalities will be your heart candy